How is the £22bn figure derived and why has headroom fallen?

Sir Keir Starmer is standing on the edge of a black hole.

The budget is looming and Downing Street believes some of the prime minister’s own MPs may move against him if it is badly received. 

Much of the jitters within Labour swirl around the filling of a black hole in the public finances that may actually be self-imposed and self-inflicted.

Niall is joined by our data and economics editor Ed Conway - who explains everything you need to know about a fiscal black hole that might not actually really exist.

Producer: Tom Gillespie

Editor: Mike Bovill